Fuel Additive and Fuel Composition

ABSTRACT

A fuel additive for a hydrocarbon based fuel that has one or more of the following Components:
         Component A; a non-ionic surfactant having the formula       

     
       
         
         
             
             
         
       
     
     wherein R is an alkyl radical having from 4 to 20 carbon atoms, preferably 6 to 10 carbon atoms, and n is an integer of from 2 to 8;
         Component B; a compound selected from the group consisting of partially sulfonated naphthalene formaldehyde condensates, polymer condensates of linear alkyl benzene sulfonic acids, and naphthalene sulfonic acids with formaldehyde and mixtures thereof;   Component C; a polycarboxylate-type material comprising at least one of a ammonium polyacrylate, a polyacrylate derivative, a hydrophobic copolymer, or a hydrophobically modified acrylic polymer having a pH of from about 6.0 to about 7.0;   Component D; a finely divided poly alpha olefin; or   Component E; any combination of A, B, C, or D.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Application No. 61/526,966filed on Aug. 24, 2011, the disclosure of which is incorporated hereinby reference for all purposes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to fuel additives and more particularly,to fuel additives exhibiting excellent detergency in the intake systemsand combustion chambers of gasoline engines and in nozzles of dieselengines. The invention also relates to fuel compositions containing suchadditives.

2. Description of the Prior Art

Sludge and/or other objectionable deposits formed in internal combustionengine fuel systems and combustion chambers of automobiles areresponsible for engine trouble, of abnormal rise in carbon monoxide andunburned hydrocarbon concentrations in the exhaust gases. It has thusfar been proposed to use certain fuel additives, typically gasolinedetergents for removing or otherwise preventing deposits in carburetors,electronic fuel injectors, intake valves, combustion chambers and otheroperative parts of automobiles.

Intensive research efforts have been made in the automobile industry toeliminate or alleviate the adverse effect of exhaust gases from thehuman body and the environment, together with efforts for fuelconsumption reduction. Accordingly, there has been a growing demand foreffective and advantageous fuel additives, which are more effective andadvantageous vis-à-vis preventing the buildup of sludge or other suchdeposits in the injector, intake system and combustion chamber of agasoline engine.

Such additives are also useful in preventing the buildup of enginedeposits formed in the injection nozzles of diesel engines caused bychanges and delays in fuel flow rate which results in deterioratingrunning performance and more harmful exhaust gases.

BRIEF SUMMARY OF THE INVENTION

In one aspect, the present invention is directed to a fuel additivewhich can dramatically reduce the buildup of deposits in an internalcombustion engine, particularly in the intake system and combustionchamber thereof.

In another aspect, the present invention involves a compositioncomprising an internal combustion fuel; e.g., gasoline, and an additiveto reduce buildup of sludge and other unwanted deposits in thecombustion chamber of the engine.

In yet another aspect, the present invention involves an additive foruse in diesel fuel to reduce diesel engine deposits in injection nozzlesof diesel engines.

DESCRIPTION OF PREFERRED EMBODIMENTS

The fuel additive of the present invention comprises a compound whichcan be:

Component A a non-ionic surfactant having hydrophobic-hydrophilicconstituents in the molecule and having the formula:

wherein R is an alkyl radical having from 4 to 20 carbon atoms,preferably 6 to 10 carbon atoms, and n is an integer of from 2 to 8;

Component B a compound selected from the group consisting of partiallysulfonated naphthalene formaldehyde condensates, polymer condensates oflinear alkyl benzene sulfonic acids, and naphthalene sulfonic acids withformaldehyde and mixtures thereof;

Component C a polycarboxylate-type material comprising at least one of aammonium polyacrylate, a polyacrylate derivative, a hydrophobiccopolymer, or a hydrophobically modified acrylic polymer having a pHfrom about 6.0 to about 7.0;

Component D a finely divided poly alpha olefin; or

Component E any combination of A, B, C, or D.

Polymers D which are used to prepare the finely divided polymerparticles used in the compositions of the present invention are obtainedby polymerizing or copolymerizing mono-olefins containing from about 2to about 30 carbon atoms. More usually, the mono-olefins, which arepreferably alpha olefins, contain from about 4 to about 20 carbon atoms,most preferably from about 6 to about 14 carbon atoms.

Any of several well known methods for polymerizing the mono-olefins maybe employed to produce the polymeric/co-polymeric agents used in thecompositions of the present invention. A particularly suitable method isthe Ziegler-Natte process which employs a catalyst system comprising thecombination of a compound of a metal of Groups IVb, Vb, VIb, or VIII ofthe Periodic Chart of Elements, with an organo metal compound of a rareearth metal or a metal from Groups Ia, IIa, and IIIb of the PeriodicChart of the Elements. Particularly suitable catalyst systems are thosecomprising titanium halides and organo aluminum compounds. A typicalpolymerization procedure is to contact the monomeric mixture with acatalyst in a suitable inert hydrocarbon solvent for the monomers andthe catalyst in a closed reaction vessel at reduced temperaturesautogenous pressure and in a nitrogen or inert atmosphere. Methods andcatalysts used in the preparation of suitable polyolefin polymers usefulin the present invention are disclosed in the following U.S. Pat. Nos.4,289,679; 4,358,572; 4,415,704; 4,433,123; 4,493,903; and 4,493,904,all of which are incorporated herein by reference for all purposes.Polyalphaolefins used in the compositions of the present invention canbe produced by a so-called solution polymerization technique, or by bulkpolymerization methods as described, for example, in U.S. Pat. No.5,539,044, the disclosure of which is incorporated herein by referencefor all purposes.

The polymers which are used in preparing the compositions of the presentinvention are generally those of relatively high molecular weight. Ingeneral, the effectiveness of the polymers in the fuel compositionincreases as the molecular weight increases beyond a certain pointtherein. The average molecular weight of the polymers is usually over100,000 and is generally in the range of from about 300,000 to about 2million. The average molecular weight of the polymers used in theprocesses and compositions of the present invention is preferably in therange of about 500,000 to about 1.5 million. In general, usefulpolyolefins in the present invention can be characterized as highmolecular weight non-crystalline polymers.

The polyolefin of the present invention can comprise a coating orpartitioning agent, e.g., a wax. The term “wax” includes any lowmelting, e.g., <500° C., organic mixture or compound of high molecularweight which is solid at ambient temperature. The waxes contemplated bythe present invention can be natural, i.e., derived from animal,vegetable or mineral sources, e.g., fatty acid waxes, or synthetic as,for example, ethylenic polymers, waxes obtained from the Fischer-Tropschsynthesis, etc. Non-limiting examples of suitable waxes includeparaffin, micro-crystalline wax, slack or scale wax, polymethylene wax,polyethylene wax, fatty acid wax, etc. Typically, the waxes used in thecompositions of the present invention are hydrocarbon in nature and arepowders or particulates at room temperature. In addition to waxes,non-limiting examples of other suitable coating agents include talc,alumina, metal salts of a fatty acid, e.g., metal stearates, silica gel,polyanhydride polymers, etc. It will be understood that the term“coating agent” is intended to and does include components which whilenot actually coating the polymeric material, interact with the polymericmaterial in such a way, be it chemical or physical, which prevents thepolyolefin, when ground to a desired particle size, from agglomeratingto the extent that the agglomerated material constitutes a solid orsubstantially solid non-dispersable mass.

Generally speaking and when used, the coating or partitioning agent willbe present in the compositions of the present invention in an amount offrom about 1 to about 25 ppm, preferably from about 5 to about 10 ppm.

Although the fuel additive compound(s) can be added per se to the fuel,e.g., gasoline, as it is being formulated at the refinery, in many casesit is more advantageous to add the compositions in conjunction with acarrier, which can be aqueous or non-aqueous. The use of a carrier isespecially desirable if it is desired to market the fuel additivecompositions of the present invention for addition by the vehicle owneras for example when filling up at a service station or the like. Forexample, if it is desired to market the fuel additive composition in apre-packaged form for use by the end user, the carrier can be aqueous ornon-aqueous, or can be a mixture of aqueous and non-aqueous carriers orsuspending mediums. Thus for example a hydrocarbon such as gasolinecould be used as a carrier to form a “syrup” for use in pre-packagedform for end users.

Whether coated or uncoated, the polyolefin powders or particulates ofthe present invention may have an average particle size of from about 25microns to about 100 microns.

Compounds of type B are generically naphthalene-formaldehyde condensatessuch water-sulfonated naphthalene-formaldehyde condensate marketed underthe name LomarD by Geo Specialty Chemicals. Other B type compoundsinclude sulfonated or partially sulfonated naphthalene formaldehydecondensates, polymeric condensates of linear alkyl benzene sulfonicacids and naphthalene sulfonic acids with formaldehyde and mixturesthereof.

C type compounds include poly carboxylate-type materials such aspolyacrylates and polyacrylate derivatives. Such polymeric moleculescomprises repeating units of a carbon-based backbone, some or all of therepeating units having a carboxylic acid group. The carboxylic acidgroups can be neutralized to form the salts or neutralized with otherbases to form other salts, e.g., sodium salts, ammonium salts, etc. Theacid groups can also be reacted with other materials, e.g., alcohols,anhydrides, etc. to form esters, etc. In addition, various co-monomerscan be employed to alter the character and composition of the resultingpolymer. Nonlimiting examples of C type compounds are marketed under thename Hydropalat® by Cognis Deutchland GmbH. In particular it has beenfound that Hydropalat® 100 and Hydropalat® 34 are particularly useful.The latter are described as hydrophobic ammonium copolymers orhydrophobically modified acrylic acid polymers having a pH of from about6.0 to about 7.0.

While not wanting to be bound by any theory, it is believed that of thecomponents A, B, C, D listed above, one of the more useful compositionsis Component D, i.e., the polyalphaolefin, in combination with B, or Cor both.

In the discussion which follows and in respect of the right amount ofcomponents A, B, C, or D employed, all amounts are given in terms of aweight/weight basis based on the weight of fuel. In general, thefollowing ranges for the various components has been found to beeffective.

A from 0-3 ppm

B from 0.1-8 ppm

C from 0.01-5 ppm

D from 2-80 ppm

From the above it can be seen that, relative to one another, when thefuel additive comprises components B and D, Component B will be presentin an amount of from about 4 wt % to about 10 wt % and Component D willbe present in an amount of from about 90 wt % to about 99 wt %. When thefuel additive comprises components C and D, Component C will be presentin an amount of from about 0.2 wt % to about 1 wt % and Component D willbe present in an amount of from about 92 wt % to about 99 wt %. When thefuel additive comprises components B, C and D, Component B will bepresent in an amount from about 4.5 wt % to about 9 wt %, Component Cwill be present in an amount from about 0.2 wt % to 1 wt %, andComponent D will be present in an amount from about 85 wt % to about 99wt %.

It will be appreciated that the particular type and amount ofcomponents, e.g., A, B, C, D, or E, used will depend upon the fuel type,e.g., gasoline, diesel, etc. Furthermore, the amounts can be easilytailored by those of skill in the art so that for a given gasolineformulation, optimum results are obtained vis-à-vis preventing foulingand deposition.

The compositions of the present invention can include, with advantage,particularly in the case of diesel fuels, a biocide in an amount of fromabout 0.05 to about 0.3 ppm. Nonlimiting examples of typical biocidesinclude glutaraldehyde, and glutaraldehyde/quarternary ammonium compoundblend, isothiazolin, tetrahydromethyl phosphonium sulfate (THPS),2,2-dibromo-3-nitrilopropionamide, bronopol and mixtures thereof.

Additionally, although not necessary the compositions can containthickening agents such as welan gum. When present, the thickening agentwill generally be present in an amount of 0.01-1 ppm.

To illustrate the present invention, the following nonlimiting examplesare presented: In examples 1 and 2, the testing was conducting accordingto ASTM D6201-04 “Standard Test Method for Dynamometer Evaluation ofUnleaded-Existing Engine Fuel for Intake Valve Deposit Formation” usinga four cylinder Ford 2.3 L engine.

Example 1

In this example, the fuel tested was Shell V Power having ananti-fouling package and formulated in 2009-2010 and purchased at aShell refining outlet. This Shell V Power is designated herein as ShellV Power-1. Table 1 summarizes the results of testing conducting usingthe Shell V Power-1 (Test ID GA-7126), Shell V Power-1 plus fueladditive Formulation 1 (Test ID GA-7126-F1) Shell V Power plus additiveFormulation 2 (Test ID GA-7126-F2).

TABLE 1 TEST ID 1 2 3 GA-7126 Base GA-7126-F1 GA-7126-F2 Date Dec. 13,2009 Nov. 15, 2009 Apr. 27, 2010 Engine Stand 28 28 28 Stand Run Number178 177 187 ADDITIVE DATA Polymer PPM 0 15 25 Polymer Type 0 C10 C10Coating Agent 0 8 8 (MP22)¹ ppm Mill Screen 0 0.093″ 0.093″ NFC² ppm 0 22 H100³ ppm 0 0 0 X-35⁴ ppm 0 2 2 Biocide⁵ ppm 0 0.25 0.25 WG⁶ ppm 00.065 0.065 AVERAGE WEIGHTS Average IVD wt, mg 313.1 265.2 11.3 PistonTop avg wt, mg 731.8 744 629.8 CC average wt, mg 769.7 824.2 654.6AVERAGE MERIT RATINGS Valve Tulips 7.63 8.60 9.78 Intake Port 5.07 5.198.30 Runner Entrance 5.82 5.88 9.33 CC rating 6.90 6.86 6.85 Piston TopRating 7.68 7.21 7.27 ¹Micronized synthetic wax marketed by MicroPowders, Inc. ²Lomar D, sulfonated naphthalene formaldehyde condensatemarketed by Geo Specialty Chemicals ³Hydropalat-100, polymericdispersing agent marketed by Cognis GmbH ⁴Nonyl phenol 5 mole ethoxylatemarketed by Harcros ⁵Chemicide 6, marketed by Diversity TechnologiesCorp. ⁶Welan gum

Testing results based on the formulations shown in Table 1 are set forthin Tables 2-7.

TABLE 2 Deposit Weight Summary Test ID GA-7126 Cylinder Number 1 2 3 4Intake Valve Weights Report (IVD) Gross Weight (g) 104.3255 102.4564102.6419 102.3597 Tared Weight 103.9781 102.1842 102.3213 102.0474Deposit Weights (mg) 1 2 3 4 IVD Weight 347.4 272.2 320.6 312.3 AverageIVD Weight 313.1 Piston Top Deposit (PTD) Weights Gross Weight (g)23.1176 23.1192 23.1720 23.0894 Tared Weight 22.3908 22.4367 22.470022.2737 Deposit Weights (mg) 1 2 3 4 PTD Weights 726.8 682.5 702.0 815.7Average PTD Weight 731.8 Combustion Chamber Deposit (CCD) Weights GrossWeight (g) 23.1627 23.2124 22.9661 23.1840 Tared Weight 22.4483 22.452822.1989 22.3464 Deposit Weights (mg) 1 2 3 4 CCD Weights 714.4 759.6767.2 837.6 Average CCD Weight 769.7

TABLE 3 Induction System Ratings Test ID GA-7126 Valve Intake RunnerCombustion Piston Cylinder Tulip Port Entrance Chamber Top Number(merits) (merits) (merits) (merits) (merits) 1 8.90 5.00 5.88 6.98 7.702 7.30 5.10 5.75 6.92 8.00 3 7.10 5.00 5.88 6.80 7.90 4 7.20 5.12 5.756.90 7.10 Average 7.63 5.06 5.82 6.90 7.68

TABLE 4 Deposit Weight Summary Test ID GA-7126-F1 Cylinder Number 1 2 34 Intake Valve Deposit (IVD) Weights Gross Weight 102.4331 102.1305102.5896 102.5416 Tared Weight 102.1774 101.8909 102.3217 102.2438Deposit Weights (mg) 1 2 3 4 IVD Weight 255.7 239.6 267.9 297.8 AverageIVD Weight 265.2 Piston Top Deposit (PTD) Weights Gross Weight (g)22.8888 23.0568 22.9392 23.0545 Tared Weight 22.2029 22.3510 22.226222.1832 Deposit Weights (mg) 1 2 3 4 PTD Weights 685.9 705.8 713.0 871.3Average PTD Weight 744.0 Combustion Chamber Deposit (CCD) Weights GrossWeight (g) 23.2042 23.1393 23.2850 23.2757 Tared Weight 22.4616 22.406722.5165 22.2224 Deposit Weights (mg) 1 2 3 4 CCD Weights 742.6 732.6768.5 1053.3 Average CCD Weight 824.2

TABLE 5 Induction System Ratings Test ID GA-7126-F1 Valve Intake RunnerCombustion Piston Cylinder Tulip Port Entrance Chamber Top Number(merits) (merits) (merits) (merits) (merits) 1 8.60 5.40 5.75 6.88 7.502 8.70 5.15 5.75 6.88 7.28 3 8.60 5.05 6.12 6.88 7.15 4 8.50 5.15 5.906.80 6.90 Average 8.60 5.19 5.88 6.86 7.21

TABLE 6 Deposit Weight Summary Test ID GA-7126-F2 Cylinder Number 1 2 34 Intake Valve Deposit (IVD) Weights Gross Weight 102.5241 102.3995104.4911 102.1830 Tared Weight 102.5119 102.3876 104.4807 102.1723Deposit Weights (mg) 1 2 3 4 IVD Weight 12.2 11.9 10.4 10.7 Average IVDWeight 11.3 Piston Top Deposit (PTD) Weights Gross Weight (g) 23.106922.9331 23.0252 23.2095 Tared Weight 22.5250 22.4231 22.4120 22.3953Deposit Weights (mg) 1 2 3 4 PTD Weights 581.9 510.0 613.2 814.2 AveragePTD Weight 629.8 Combustion Chamber Deposit (CCD) Weights Gross Weight(g) 22.9981 22.9638 23.2264 22.9785 Tared Weight 22.4709 22.3584 22.513822.2053 Deposit Weights (mg) 1 2 3 4 CCD Weights 527.2 605.4 712.6 773.2Average CCD Weight 654.6

TABLE 7 Induction System Ratings Test ID GA-7126-F2 Valve Intake RunnerCombustion Piston Cylinder Tulip Port Entrance Chamber Top Number(merits) (merits) (merits) (merits) (merits) 1 9.80 8.18 9.01 6.80 7.102 9.70 8.18 9.48 6.99 7.40 3 9.80 8.18 9.68 6.85 7.38 4 9.80 8.34 9.156.75 7.18 Average 9.78 8.30 9.33 6.85 7.27

Example 2

This example shows another comparison using Shell V Power gasoline(Shell V Power-2) purchased at a Shell refinery outlet but having areformulated anti-fouling package which differs from the packagecontained in the Shell V Power-2 used in Example 1. The results of thevarious tests are shown in Table 8. In Table 8, results are shown forthe base gasoline Shell V Power-2 (Test ID GA-7624 Base), Shell VPower-2 with additive Formulation 3 (Test ID GA-7624-F3), Shell VPower-2 plus additive Formulation 4 (Test ID GA-7624-F4) and Shell VPower-2 plus additive Formulation 5 (Test GA-7624-F5).

TABLE 8 TEST ID GA-7624 Base GA-7622 (35N) GA-7642 (100N) GA-7624 +(100) Date Feb. 27, 2011 Mar. 14, 2011 Mar. 22, 2011 Apr. 5, 2011 EngineStand 31 31 31 31 Stand Run Number 160 161 162 163 ADDITIVE DATA PolymerPPM 0 25 25 25 Load In Fuel Polymer Type 0 C10 C10 C10 Coating Agent⁷(ppm) 0 8 8 8 Mill Screen 0 0.093″ 0.093″ 0.093″ NFC (ppm) 0 2 2 0 H100(ppm) 0 0 0.5 0.5 X-35 (ppm) 0 2 0 0 Biocide (ppm) 0 0.25 0.25 0.25 WG(ppm) 0 0.065 0.065 0.065 AVERAGE WEIGHTS Average IVD wt, mg 131.7 112.478.6 106.8 Piston Top avg wt, mg 910.4 769.6 575.4 652.8 CC average wt,mg 965 814.6 609.1 673.3 AVERAGE MERIT RATINGS Valve Tulips 8.83 7.788.88 7.93 Intake Port 6.55 5.97 7.84 7.90 Runner Entrance 8.39 6.60 9.679.53 CC rating 6.68 6.49 6.60 6.21 Piston Top Rating 7.07 6.98 7.08 7.04⁷Calcium Stearate

Example 3

In this example, testing was conducted pursuant to European standardsprocedure CEC F-05-93 for testing inlet valve cleanliness using an MB102 E engine. The gasoline employed was Unleaded Regular MG 91 to whichcontains 300 ppm of an anti-fouling additive, Keropur® marketed by BASFto form a base gasoline. The base gasoline was then mixed with variousother components of the present invention in various amounts and testedfor intake valve deposits (IVD). The results are shown in Table 9,below.

TABLE 9 X-35, NFC, PAO, Average IVD ppm ppm ppm wt in mg Base 0 0 0 245Formula 1 1.66 0.33 5 116 Formula 2 0.33 1.66 5 50 Formula 3 0 4 5 90Formula 4 0 8 5 51 Formula 5 0 24 5 113 Formula 6 0 8 10 125 Formula 7 22 25 195

As can be seen from the above data, the fuel additive compositions ofthe present invention show remarkable results in terms of reducingengine deposits in the combustion train of the engine.

As the data shows, various combinations of the various components A, B,C, or D can be employed and, as noted above, can be tailored by thoseskilled in the art of fuel blending to achieve optimum results. However,in virtually all cases, the results achieved using the compositions ofthe present invention, regardless of the amount or type of the variouscomponents, gives better results in terms of reducing combustion traindeposits.

Although specific embodiments of the invention have been describedherein in some detail, this has been done solely for the purposes ofexplaining the various aspects of the invention, and is not intended tolimit the scope of the invention as defined in the claims which follow.Those skilled in the art will understand that the embodiment shown anddescribed is exemplary, and various other substitutions, alterations andmodifications, including but not limited to those design alternativesspecifically discussed herein, may be made in the practice of theinvention without departing from its scope.

What is claimed is:
 1. A fuel additive for a hydrocarbon based fuelcomprising at least one of: Component A a non-ionic surfactant havinghydrophobic-hydrophilic constituents in the molecule and having theformula:

wherein R is an alkyl radical having from 4 to 20 carbon atoms,preferably 6 to 10 carbon atoms, and n is an integer of from 2 to 8;Component B a compound selected from the group consisting of partiallysulfonated naphthalene formaldehyde condensates, polymer condensates oflinear alkyl benzene sulfonic acids, and naphthalene sulfonic acids withformaldehyde and mixtures thereof; Component C a polycarboxylate-typematerial comprising at least one of a ammonium polyacrylate, apolyacrylate derivative, a hydrophobic copolymer, or a hydrophobicallymodified acrylic polymer having a pH from about 6.0 to about 7.0;Component D a finely divided poly alpha olefin; or Component E anycombination of A, B, C, or D.
 2. The fuel additive of claim 1,comprising Component D and at least one of Component B or Component C.3. The fuel additive of claim 2, comprising Component D and Component B.4. The fuel additive of claim 2, comprising Component D and Component C.5. The fuel additive of claim 2, comprising Component D, Component B andComponent C.
 6. The fuel additive of claim 1, wherein said polyalphaolefin is produced from alpha olefins containing between 4-20 carbonatoms.
 7. The fuel additive of claim 6, wherein said polyalpha olefincontains between 6-14 carbon atoms.
 8. The fuel additive of claim 1,wherein said polyalpha olefin is produced from alpha olefins having anaverage of 10 carbon atoms.
 9. The fuel additive of claim 6, wherein themolecular weight of the polyalpha olefin is from about 300,000 to about2,000,000.
 10. The fuel additive of claim 6, wherein said polyalphaolefin has a particle size of from 25 microns to 100 microns.
 11. Thefuel additive of claim 5, wherein Component B is present in an amount offrom about 4.5 wt % to about 9.0 wt %, Component C is present in anamount from about 0.2 wt % to about 1.0 wt %, and Component D is presentin an amount from about 85 wt % to about 99 wt %.
 12. The fuel additiveof claim 3, wherein Component B is present in an amount from about 4.0wt % to about 10 wt %, and Component D is present in an amount fromabout 90 wt % to about 99 wt %.
 13. The fuel additive of claim 4,wherein Component D is present in an amount from about 92 wt % to about99 wt % and Component C is present in an amount from about 0.2 wt % toabout 1.0 wt %.
 14. The fuel additive composition of claim 1 comprisingan adjunct selected from the group consisting of biocides, thickeningagents and mixtures thereof.
 15. A fuel composition comprising ahydrocarbon containing fuel and a fuel additive according to claim 1.16. The fuel composition of claim 15, wherein the hydrocarbon fuelcomprises diesel.
 17. The fuel composition of claim 15, wherein thehydrocarbon fuel comprises gasoline.